Thyroid Cancer Risk from Exposure to Ionizing Radiation: A Case Study in the Comparative Potency Model

Considerable controversy exists about the relative risk of thyroid cancer following exposure to external radiation compared to the risk after exposure to internally deposited 131I. The human epidemiological data are equivocal, and studies are not directly comparable owing to differing ages at exposure, dose ranges, and periods of follow-up. Limited experimental data at low dose ranges support the hypothesis of equal potency in animals. This report utilizes a relative potency model to reconcile data from different sources, and to provide an estimate of thyroid cancer risk following human exposure to 131I. We utilize data from epidemiological studies of external radiation and 131I exposure in humans and data from an experimental animal study. This analysis shows that the data provide no compelling evidence to suggest that the risks accompanying external radiation or 131I exposure are different.     

Variation of Consumer Contact with Household Products: A Preliminary Investigation

Little information is available on product use by consumers, which severely hampers exposure estimation for consumer products. This article describes actual contact with several consumer products, specifically dishwashing detergents, cleaning products, and hair styling products. How and where products are handled, as well as the duration, frequency, and amount of use were studied by means of diaries, in‐home observations, and measurements. This study addressed the question, “To what extent are frequency, duration, and amount of use associated?” Findings showed that there was a large intra‐ as well as interindividual variation in frequency, duration, and amount of use, with the interindividual variation being considerably larger. At the same time, results showed that, for a given activity, users tended to follow their own routine. Few relations were found among frequency, duration, and amount of use. It was concluded that among persons, frequency, duration, and amount of product act in practice as independent parameters. Diaries appear to be quite suitable for gaining insight into frequently used products. Observations of usage, recorded on video, were indispensable for obtaining particular information on product use. In addition, home visits enabled the collection of specific measurements. Although diaries and home visits are time‐consuming, the combination provided insight into variation as well as relations among frequency, duration, and amount of use.     

Exposure to Environmental Tobacco Smoke in the Workplace and the Impact of Away-From-Work Exposure

Concentrating on exposure in workplaces where smoking occurs, we examined environmental tobacco smoke (ETS)-related concentration data from the 16-City Study.^(1,2) This study involved a large population of nonsmokers, used personal monitors, and encompassed a wide selection of ETS-related constituents. This first article in a series of three describes the 16-City Study, considers the impact of demographic variables, and concludes that these variables did not explain differences in exposure to ETS. We compared 16-City Study concentrations obtained in the workplace to previously reported workplace concentrations and determined that data from this study were representative of current ETS exposure in nonmanufacturing workplaces where smoking occurs. Considering factors other than demographic factors, we found that, not surprisingly, the number of cigarettes observed in the workplace had an impact on exposure concentrations. Finally, we compared people from homes where smoking occurs with people from nonsmoking homes and found that people from smoking homes observed more smoking in the workplace and experienced higher concentrations of ETS-related compounds in the workplace, even when they observed the same number of cigarettes being smoked in the workplace. In two subsequent articles in this series, we discuss relationships between various ETS markers and provide estimates of distributions of doses to nonsmoking workers employed in workplaces where smoking occurs.     

Evaluating the Effectiveness of Risk-Reduction Strategies for Consumer Chemical Products

Communication about risks offers a voluntary approach to reducing exposure to pollutants. Its adequacy depends on its impact on behavior. Estimating those impacts first requires characterizing current activities and their associated risk levels, and then predicting the effectiveness of risk-reduction strategies. Characterizing the risks from chemical consumer products requires knowledge of both the physical and the behavioral processes that influence exposures. This article presents an integrated approach that combines consumer interviews, users' beliefs and behaviors, and quantitative exposure modeling. This model was demonstrated in the context of consumer exposure to a methylene chloride-based paint stripper, showing how it could be used to evaluate current levels of risk and predict the effectiveness of proposed voluntary risk-reduction strategies.     

Estimates of Lifetime-Absorbed Daily Doses from the Use of Personal-Care Products Containing Polyacrylamide: A Monte Carlo Analysis

Estimates of the lifetime-absorbed daily dose (LADD) of acrylamide resulting from use of representative personal-care products containing polyacrylamides have been developed. All of the parameters that determine the amount of acrylamide absorbed by an individual vary from one individual to another. Moreover, for some parameters there is uncertainty as to which is the correct or representative value from a range of values. Consequently, the parameters used in the estimation of the LADD of acrylamide from usage of a particular product type (e.g., deodorant, makeup, etc.) were represented by distributions evaluated using Monte Carlo analyses.((1-4)) From these data, distributions of values for key parameters, such as the amount of acrylamide in polyacrylamide, absorption fraction, etc., were defined and used to provide a distribution of LADDs for each personal-care product. The estimated total acrylamide LADD (across all products) for males and females at the median, mean, and 95th percentile of the distribution of individual LADD values were 4.7 x 10(-8), 2.3 x 10(-7), and 7.3 x 10(-7) mg/kg/day for females and 3.6 x 10(-8), 1.7 x 10(-7), and 5.4 x 10(-7) mg/kg/day for males. The ratio of the LADDs to risk-specific dose corresponding to a target risk level of 1 x 10(-5), the acceptable risk level for this investigation, derived using approaches typically used by the FDA, the USEPA, and proposed for use by the European Union (EU) were also calculated. All ratios were well below 1, indicating that all the extra lifetime cancer risk from the use of polyacrylamide-containing personal-care products, in the manner assumed in this assessment, are well below acceptable levels. Even if it were assumed that an individual used all of the products together, the estimated LADD would still provide a dose that was well below the acceptable risk levels.     

农产品销量预测的支持向量机方法

运用支持向量机(Support Vector Machine,SVM)智能预测方法对农产品的消费市场需求进行动态预测。为提高农产品销量预测精度,充分考虑了农产品供需随天气变化、气候条件、节假日等因素的影响而动态变化的情况,将这些影响因素纳入农产品销量预测中,运用模糊理论进行模糊化处理;在此基础上提出以支持向量机方法为主、多方法融合为辅的智能预测系统,对农产品销量进行动态预测。实际算例验证了这一智能预测系统的精确性。     

Supply Chain Strategies for Perishable Products: The Case of Fresh Produce

This paper examines supply chain design strategies for a specific type of perishable product—fresh produce—using melons and sweet corn as examples. Melons and other types of produce reach their peak value at the time of harvest; product value deteriorates exponentially post‐harvest until the product is cooled to dampen the deterioration. Using the product's marginal value of time (MVT), the rate at which the product loses value over time in the supply chain, we show that the appropriate model to minimize lost value in the supply chain is a hybrid of a responsive model from post‐harvest to cooling, followed by an efficient model in the remainder of the chain. We also show that these two segments of the supply chain are only loosely linked, implying that little coordination is required across the chain to achieve value maximization. The models we develop also provide insights into the use of a product's MVT to develop supply chain strategies for other perishable products.     

Estimation of Dietary Exposure to Chemicals: A Case Study Illustrating Methods of Distributional Analyses for Food Consumption Data

There are a number of sources of variability in food consumption patterns and residue levels of a particular chemical (e.g., pesticide, food additive) in commodities that lead to an expected high level of variability in dietary exposures across a population. This paper focuses on examples of consumption pattern survey data for specific commodities, namely that for wine and grape juice, and demonstrates how such data might be analyzed in preparation for performing stochastic analyses of dietary exposure. Data from the NIAAA/NHIS wine consumption survey were subset for gender and age group and, with matched body weight data from the survey database, were used to define empirically-based percentile estimates for wine intake (μl wine/kg body weight) for the strata of interest. The data for these two subpopulations were analyzed to estimate 14-day consumption distributional statistics and distributions for only those days on which wine was consumed. Data subsets for all wine-consuming adults and wine-consuming females ages 18 through 45, were determined to fit a lognormal distribution ( R ²= 0.99 for both datasets). Market share data were incorporated into estimation of chronic exposures to hypothetical chemical residues in imported table wine. As a separate example, treatment of grape juice consumption data for females, ages 18–40, as a simple lognormal distribution resulted in a significant underestimation of intake, and thus exposure, because the actual distribution is a mixture (i.e., multiple subpopulations of grape juice consumers exist in the parent distribution). Thus, deriving dietary intake statistics from food consumption survey data requires careful analysis of the underlying empirical distributions.     

免费商品对互补产品扩散的影响

本文基于互补产品扩散模型,在考虑价格策略以及重复购买与批量购买的消费者行为下,建立了免费商品赠送对互补产品扩散影响的优化模型群。通过模拟计算,分析结果表明免费商品的赠送对互补产品的扩散有促进作用,同时赠送互补产品优于仅赠送其中一种产品。在产品引入前进行免费商品赠送的边际效应要高于在其他时期赠送,形成"首期赠送效应"。当消费者有批量购买行为时,企业值得赠送更多的免费商品来提高消费者对产品的了解程度,以获得更高的利润。在对首期赠送水平的参数灵敏度分析后,给出了扩散过程中各个参数选取对于赠样水平的影响趋势与范围。在此基础上,为企业在实际促销决策中给出了具体的应用步骤。     

案例研究方法严谨性测度研究

针对国内案例方法理论研究和实践现状,提出案例研究方法严谨性问题。在引介国外前沿案例研究严谨性方法论的基础上,结合自己的学习型理解和案例研究实践,通过纳入国内案例研究的情境因素,加以消化吸收,以案例研究方法的效度和信度关切为聚焦,初步厘清了案例研究方法严谨性的内涵和指标体系,构建出具有实际操作性的严谨性测度框架,丰富并提高了国内案例研究严谨性方法论,并且选取名刊名家最新案例研究型论文进行实证测度,发现了案例研究方法严谨性领域的国内外较大差距,指明了我们未来的努力方向。     

部分信息下生鲜农产品采购外包问题研究

针对生鲜农产品的固有属性导致的采购风险,以及企业将一些业务如物流、采购等外包给第三方物流企业(3PL, Third Party Logistics),从而专注于自身核心业务发展的现实,建立了零售商和3PL的博弈模型,对比分析了部分需求信息下3PL采购和零售商采购对零售商和3PL的最优决策、利润,以及供应链系统利润的影响。研究表明,当正向需求风险较大时,3PL对生鲜农产品实际需求的判断较准确;当需求风险较小时,零售商对生鲜农产品实际需求的判断较准确。研究还发现,在绝大部分情况下,3PL采购对供应链系统是不利的。只有当正向需求风险很大,或生鲜农产品损耗率非常大,或损失分担比例很高时,3PL采购才能够增加供应链系统的利润。然而,在3PL采购提高供应链系统利润的条件下,3PL的利润低于同等条件下零售商采购时的利润。建议此时零售商通过采取返还给3PL一定利润的方式来促使3PL同意参与采购管理,以增加零售商、3PL和供应链系统的利润,提高供应链的竞争力。     

延迟支付条件下易逝品的最优订货决策研究

本文在考虑延期支付的情况下构建了二级供应链关于易逝品的最优订货决策模型,其中供应链由单个供应商和多个面临资金约束的零售商组成。在不允许缺货的情况下,供应商为零售商提供延迟支付来缓解零售商的资金压力,同时零售商对产品的定价将随易逝品的价值变质而变化。本文利用遗传算法对模型进行了算例分析,同时对模型中的相关参数进行了敏感性分析。结果表明,延迟支付能够提高供应链总利润并降低风险,从而有利于供应链整体效益的提高。在延期支付条件下,供应链各成员获得的收益增量存在较大差距,其中供应商能够获得更多收益。最后,通过敏感性分析,我们还发现产量及易逝品保质期的变动会对供应链整体利润产生不同程度的影响。     

企业家道德发展阶段模型多案例探索研究

通过理论和实践研究提出了企业家道德发展四阶段理论,把企业家道德发展划分为道德失范性阶段、道德遵从性阶段、道德资本性阶段和道德皈依性阶段,并构建了企业家道德发展阶段模型。基于此探讨了企业家道德进化的方略问题。这有助于用动态发展的眼光看待企业家道德,从而指导企业家审视其道德状态,明确其道德修炼方向。     

控股股东对上市公司现金股利政策影响的实证研究

本文从最终控制人的概念出发,以控股股东的经济性质、所有权与控制权的分离度以及集团控制性质作为控股股东的特征变量,分别采用Logistic模型和多元线性回归模型分析了控股股东对上市公司现金股利分配倾向和分配力度的影响。研究结果发现控股股东的上述3个特征显著地影响了上市公司的现金股利分配倾向和分配力度。     

基于跨案例扎根分析的商业模式结构模型研究

以75个实际企业商业模式成功案例为样本,应用扎根理论的Strauss三阶段编码方法进行跨案例分析,构建商业模式结构模型。以迭代式开放性编码对案例中描述商业模式的变量进行概念化和类属化,依据主轴编码的典范模式将各类属按性质分布于具有因果关系的6个层次,将每个层次的类属性质聚类为具有三级结构的商业模式构件,建立一个包含15个构件和6个层次的二维商业模式结构模型,并以实际企业案例详细说明模型的应用。研究结果表明,构建的模型有效改进了现有商业模式结构研究在构件细化、构件全面性和模型开放性等方面存在的不足,且为解释性模型和形式理论,使模型不仅可以跨情境地应用于商业模式描述、商业模式评估和商业模式创新策略归纳,也为研究更深层次商业模式问题奠定了良好的基础,并对企业创新和改进商业模式提供指导。     

基于GERT随机网络的废弃回收预测模型研究

在阐述回收处理业务流程的基础上,分析其不确定性;运用随机网络系统模型的相关理论构建GERT网络模型,探讨产品回收再制造零部件和可再生材料的预测模型。该模型既可以预测出废弃产品返回数量、回收处理过程中的再造零部件和可再生材料的比例和数量,又可以预测出它们的期望返回时间。最后,以打印机的回收再制造为例,对模型进行了实际应用。     

价格折扣呈现方式对促销效果影响的实证研究

本文按照信息处理这一研究框架,通过两个实验研究了基于金额和基于百分比的两种价格折扣呈现方式对消费者感知价值、购买意愿的影响及其边界条件。由于消费者头脑中处理基于百分比的价格折扣信息比处理基于金额的价格折扣信息具有更大的难度,从而消费者能够对后者产生更高的感知价值和购买意愿。又因为价格折扣计算难易程度和促销品价格是价格呈现形式对影响感知价值的两个边界条件,且价格折扣对购买意愿的影响是通过感知价值这一中介变量得以实现的,因此对于容易计算的价格折扣或者低价促销品,两种折扣形式对消费者感知价值的影响差异将消失。     

企业间关系强度对关系价值机制影响的实证研究——基于企业间相互依赖性视角

作为相关领域中首例着眼于企业间关系强度与关系价值机制间关系的研究,本文以我国运动用品制造业企业为样本,以企业间相互依赖性为主要视角,就企业间关系强度对该关系价值机制的影响机制进行了实证研究。结果表明,企业关系网络中特定关系安排的强度对关系本身的价值及两类价值机制的运用水平均会产生显著的影响,同时也会影响到该关系安排中双方主体企业间的联合依赖程度与依赖的不对称性。进而,作为关系强度与关系价值机制间的重要中介机制,联合依赖性与依赖非对称性也显著影响着成员企业对关系价值机制的运用方式。本研究的相关结论对于进一步的研究与企业管理实践均有一定价值。     

An Empirical Study of the Impact of Just-in-Time Task Scope Versus Just-in-Time Workflow Integration on Organizational Design

The research tests a theory of JIT as a technology having task scope versus workflow integration dimensions. The results show that JIT task scope predicts JIT workflow integration, and that only the former is associated with organizational designs that are more specialized, decentralized, integrated, and reliant on formal performance measurement control. The findings imply that organizational structure does not necessarily follow from workflow structure. Rather, both organizational structure and workflow structure follow from the knowledge capital that JIT task scope represents.     

Environmental Tobacco Smoke Revisited: The Reliability of the Data Used for Risk Assessment

Several epidemiological studies have found a weak, but consistent association between lung cancer in nonsmokers and exposure to environmental tobacco smoke (ETS). In addition, a purported link between such exposure and coronary heart disease (CHD) has been of major concern. Although it is biologically plausible that ETS has a contributory role in the induction of lung cancer in nonsmoking individuals, dose-response extrapolation-supported by the more solid database for active smokers-gives an additional risk for lung cancer risk that is more than one order of magnitude lower than that indicated by major positive epidemiological studies. The discrepancy between available epidemiological data and dosimetric estimates seems, to a major part, to reflect certain systematic biases in the former that are difficult to control by statistical analysis when dealing with risks of such low magnitudes. These include, most importantly, misclassification of smoking status, followed by inappropriate selection of controls, as well as certain confounding factors mainly related to lifestyle, and possibly also hereditary disposition. A significant part of an association between lung cancer and exposure to ETS would disappear, if, on the average, 1 patient out of 20 nonsmoking cases had failed to tell the interviewer that he had, in fact, recently stopped smoking. In the large International Agency for Research on Cancer (IARC) multicenter study even lower misclassification rates would abolish the weak, statistically nonsignificant associations that were found. In the former study an apparent significant protective effect from exposure to ETS in childhood with respect to lung cancer later in life was reported, a most surprising finding. The fact that the mutation spectrum of the p53 tumor suppressor gene in lung tumors of ETS-exposed nonsmokers generally differs from that found in tumors of active smokers lends additional support to the notion that the majority of tumors found in ETS-exposed nonsmokers have nothing to do with tobacco smoke. The one-sided preoccupation with ETS as a causative factor of lung cancer in nonsmokers may seriously hinder the elucidation of the multifactorial etiology of these tumors. Due to the high prevalence of cardiovascular disease in the population, even a modest causal association with ETS would, if valid, constitute a serious public health problem. By pooling data from 20 published studies on ETS and heart disease, some of which reported higher risks than is known to be caused by active smoking, a statistically significant association with spousal smoking is obtained. However, in most of these studies, many of the most common confounding risk factors were ignored and there appears to be insufficient evidence to support an association between exposure to ETS and CHD. Further, it seems highly improbable that exposure to a concentration of tobacco smoke at a level that is generally much less than 1% of that inhaled by a smoker could result in an excess risk for CHD that-as has been claimed-is some 30% to 50% of that found in active smokers. There are certainly valid reasons to limit exposure to ETS as well as to other air pollutants in places such as offices and homes in order to improve indoor air quality. This goal can be achieved, however, without the introduction of an extremist legislation based on a negligible risk of lung cancer as well as an unsupported and highly hypothetical risk for CHD.